Abstract
A transient computational fluid dynamics (CFD) modelling approach was used to study the complex multi-phase flow in an argon-stirred industrial scale ladle with a nominal capacity of 150 tons. During the stirring process, when gas was injected through the porous plug from the bottom into the steel bath, it breaks up into bubbles and infringes the slag layer creating an open-eye. The volume of fluid model was used to investigate the open-eye formation process in the simulations. In the numerical simulations, the open-eye area changed from 0.7 to 2.24 m2 with the increment of argon flow rate from 200 to 500 NL/min for slag layer thickness of 40 cm. Furthermore, the influence of slag layer height on the open-eye area was investigated. An argon flow rate of 200 NL/min was able to break the slag layer for slag layer height of 40 cm, and the open-eye formation was not possible for the same flow rate when the slag layer height was elevated from 40 to 55 cm. The numerical simulation results were validated against industrial measurements carried out at Outokumpu Stainless located in Tornio, Finland. The numerical simulation results of dynamics and time-averages of the slag area showed a good agreement when compared to the industrial measurements. To conclude, it is necessary to define gas flow rate based on the slag layer height to have an open-eye suitable for alloying.
Highlights
In ladle metallurgy, gas stirring is largely used to homogenize the composition of alloy elements, temperature in the molten steel, and to remove inclusions
The argon gas, which was injected into the bath through the nozzle, splits up into bubbles and impinge the slag layer at high flow rates forming a open-eye
The results indicate that the gas flow rate and slag layer height play an important role in generating a suitable open-eye size for alloying purposes
Summary
Gas stirring is largely used to homogenize the composition of alloy elements, temperature in the molten steel, and to remove inclusions. Li et al [18,19,20,21,22] performed both experiments and simulations to study the formation of open-eye process and slag/steel/gas interface shape for various flow rates in a water model ladle. Ramasetti et al [23,26] performed both experiments and numerical simulations in a 1/5 scale water model for investigating the influence of gas flow rate and slag layer height on the open-eye area with single and dual-plug configurations. The influence of gas flow rate and slag layer height on open-eye formation was investigated through industrial measurements and numerical simulations. As for the simulation part, the VOF model was used to investigate the slag/steel/gas behavior in the ladle
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